New Study Explains Why Stress Makes You Fat

By: Julie Hand
January 24, 2018

New Study Explains Why Stress Makes You Fat

Is snacking sabotaging your weight-loss efforts? New research shows you’re particularly vulnerable at night. A new study[1], published in the International Journal of Obesity, reveals that levels of the hunger hormone, ghrelin, are higher in the evening – and stress raises them even more. This can lead to mindless snacking and binge eating in those who are prone to it.

Research shows stress increases hunger hormones in the evening

Previous research demonstrated that ghrelin rises in response to stress in the daytime. Intrigued to understand how stress affects hunger later in the day, researchers crafted an experiment to observe participants’ hunger and stress hormones at different times. They recruited 32 overweight participants (19 men and 13 women), 18 to 50 years of age – half had been diagnosed with binge eating disorder. They had body mass indices (BMI) ranging from 28 to 52, though were otherwise healthy.

After fasting for 8 hours, the participants received a 608-calorie liquid meal at either 9 am or 4 pm. Each participant then took part in a standard experimental stress test 130 minutes after the meal, whereby a digital camera recorded their facial expressions with their non-dominant hand submerged in a bucket of cold water. Afterward, the researchers measured the participants’ stress and hunger hormones via blood tests. Participants also rated their subjective hunger and fullness levels on a numeric scale. Finally, 30 minutes after the stress test, participants received access to a buffet of pizzas, snack chips, cookies, chocolate-covered candies, and water.

The results? The time of day drastically impacted hunger levels – the self-reports noted greater appetite in the evening versus the morning. As well, the binge eating disorder group showed signs of higher levels of ghrelin in the evening. Regarding the stress test results, stress levels peaked and hunger levels rose in both the morning and the evening – however, there were higher levels of ghrelin in the evening. This suggests that stress impacts ghrelin more in the evening than in the daytime.  

Whether you struggle with binge eating disorder or overeat occasionally on stressful nights, there are steps you can take to keep your hunger hormones and stress levels in check.

How to keep your ghrelin levels in check

Let’s tackle ghrelin first. Ketosis – the state your body is in when it converts fat for fuel rather than carbs – suppresses your appetite (ghrelin levels) like nothing else[2]. To learn more about how to reset your appetite with ketosis, read here. Even if you don’t want to practice a ketogenic diet, eating meals that are high in healthy fats and low in carbohydrates keeps your blood sugar level and appetite stable, so you’re less prone to snacking.

Manage stress by combating “decision fatigue”

Second, get a handle on your stress levels. As the day wears on, it’s harder to stick with your resolve. That’s because of something called decision fatigue. Simply put, the more decisions you have to make, the worse your judgment becomes. You can strengthen your willpower – and cut down on stress – by cutting down on daily decision-making. Simple steps, like meal-prepping and choosing your wardrobe for the week, make it easier to get out the door in the morning. It sounds trivial, but all of those little decisions you make throughout the day add up. By nighttime, you will thank yourself if you’ve made the day easier by taking out the daily decisions that can lead to decision fatigue by nightfall. By taxing your brain with fewer decisions, you’ll be able to better resist snacking at night.

Related: Ways to Hack Your Nervous System To Consciously Manage Stress

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